This project is concerned with the relationship between the structure and activity of proteins, particularly those of the immunoglobulin system and those capable of interacting with lymphoid cells. Recent studies include: isolation and characterization of a new group of antibodies capable of interacting with cell surface carbohydrates on lymphoid cells; analysis of the dynamics of a system of submembraneous proteins believed to be responsible for modulating the mobility and distribution of lymphocyte receptors as well as various signals mediating cell proliferation; and examination of the development of the immune system at the level of individual animals. In addition, detailed structural studies are being carried out to determine the amino acid sequences and three-dimensional structures of Bence Jones proteins, immunoglobulins, Beta 2-microglobulin from different species, and a variety of lectins. The purpose of these studies is to determine the relationship between the amino acid sequences and the folding of proteins as well as to correlate the structures of these proteins with their biological activities. The primary structures of several other cell surface antigens and serum proteins are being examined for homology with the immunoglobulins.